The present invention is directed generally to a waterbed mattress including a bellows spring insert for auxiliary support for loads placed on the mattress above the insert.
Improved sleep is experienced on a waterbed mattress, compared to sleep on a conventional mattress, because the support forces are more uniformly distributed across the body thereby substantially eliminating localized pressure points. This same characteristic, however, makes the top surface of a waterbed mattress more susceptible to deflection by a concentrated load such as when one sits or kneels on a waterbed mattress. Internal baffling systems and foam and fiber fillers have been incorporated into waterbed mattresses to eliminate wave action and restrict the flow therein. These, however, have only indirectly improved the resistance of a waterbed mattress surface to deflection by a concentrated load.
Previous attempts have been made to incorporate springs within a waterbed mattress. Callaway U.S. Pat. No. 4,245,363, for example, provides coil springs within an annular chamber surrounding a central waterbed mattress bladder to support one seated on the edge of a waterbed mattress. An alternate embodiment shows coil springs within the waterbed mattress bladder as well. Such a mattress, however, requires structure for supporting the individual coils and for preventing puncture of the mattress walls, all of which increase the expense of the mattress. The complexity inherently presents manufacturing problems and an increased number of potential failure points on the mattress.
Accordingly, a primary object of the invention is to provide an improved bellows spring insert for a waterbed mattress.
Another object is to provide such an insert which includes a plurality of bellows spring units having opposite open ends.
Another object is to provide such an insert which does not hold water and therefore does not resist draining of the waterbed mattress.
Another object is to provide a spring insert in which a plurality of bellows spring units are arranged and supported relative to one another.
Another object is to provide a spring insert wherein a generally flat panel has a plurality of openings for receiving and arranging respective bellows spring units.
Another object is to provide such a spring insert which does not require mechanical attachment to the waterbed mattress.
Another object is to provide such a bellows spring insert which combines mechanical spring resistance with an underlying or overlying perforated sheet to form flow resisting chambers for effecting shock absorption as well as spring resistance to concentrated loads on a waterbed mattress.
Another object is to provide such a spring insert which is free of attachment to the bottom wall of the mattress but which functions substantially as if it were so attached.
Another object is to provide an improved waterbed mattress with spring support to supplement the flotation support of a conventional waterbed mattress.
Another object is to provide an improved waterbed mattress including the spring insert of the invention.
Another object is to provide such an improved waterbed mattress and spring insert which are simple and rugged in construction, economical to manufacture and efficient in operation.